Attachment theory claims that inner working models of attachment substantially control behavioral and emotional regulation. There are different levels of organization of the attachment system following a developmental sequence from basic attachment behaviors at newborn age to a procedural organization in terms of behavioral strategies at the end of the first year to a representational organization later on. Also, the organismic systems underlying emotions and emotional regulation may occur and may be described on different organizational levels. Inner working models are seen as regulatory mechanisms for the interplay between the different organismic systems underlying emotions and emotional regulation. This paper will concentrate on biobehavioral organization. Combining assumptions of attachment theory with assumptions about biobehavioral function may provide the possibility of validating theoretically derived interpretations of the attachment system. Including the physiological processes in addition to the psychological processes enables us to test assumptions about the function of the inner working model with respect to processes that are not accessible by verbal communication and that are not expressed through overt behavior. The paper will provide theoretical and empirical evidence for the contribution of the inner working model of attachment to emotional perception, emotional expression and the coherence of inter-modal organization. The empirical findings suggest that from a developmental perspective the inclusion of different levels of regulation may provide possibilities of studying continuity and stability of individual differences of the attachment system during the life-course both within and across levels.